Upgrading the energyefficiency of hotels to meetthe Net Zero Energy Hotel

requirements

Student Name: Evangelos PetousisSID:3304150009

Supervisor: Dr. Theodoros Theodosiou

SCHOOL OF SCIENCE & TECHNOLOGYA thesis submitted for the degree of

Master of Science (MSc) in Energy Building Design

December 2018

THESSALONIKI-GREECE

ABSTRACT

The present dissertation deals with the energy performance of hotels and contains abibliographic and experimental part. Hotels, being one of the most energy consuming parts ofa country’s building stock, are one of the most difficult and interesting examples of an energyperformance analysis for buildings. What is more, their design is not focused mainly onenergy conservation or maximization of a worker’s performance like most similarly hugebuildings of the commercial sector. Their focus is depicted on energy use minimization, inparallel with strong reduction of environmental impact. This is reflected on most technicalguides, such as ASHRAE and the Greek Regulation for Energy Performance of Buildings.

However, the main purpose of the dissertation is not to study a theoretical scenario of a newhotel being built, which would allow the author a great deal of freedom in makingassumptions, such as an unlimited theoretical budget, or choosing the most beneficial coursesof actions regardless of cost or feasibility, such as choosing the optimal location or havingenough available space to install any type of equipment. The main purpose is to evaluate areal life example with all the hindrances and restrictions one would expect from such a caseand assess if this hotel building can be transformed into net zero. The hotel which isevaluated is Royal Olympic Hotel, located in the urban environment of Athens. Thisdirection is also reflected on the bibliographical part which is also focused on studiesperformed on various hotel facilities around the world. The bibliographical part deals withcases of analysis of energy audit in hotels, the assessment of affordable and “cheap”improvements (a methodology which is preferred by the majority of the board of directorsand the management in most hotels) and contains case studies of real life hotels whichcompare different models, methodologies and technologies. The implementation of smartenergy management techniques and practices is investigated, as well as case studies ofexisting net zero energy buildings.

The experimental part is focused on the information collected during the audit that was usedto perform an energy simulation of the premises through the Energy Plus Simulation Tool,after the initial design of the building in Google Sketchup and Open Studio environment. Thefinancial feasibility of installing Renewable energy Sources Systems is also examined. UsingEnergy Plus, it was estimated that approximately 130.000 kWh could be produced on anannual basis. The cost was estimated by using retail prices and adding other factors(installation cost and maintenance) the total cost was estimated at 102.000 euros. Of course,this production of renewable energy would not be able to cover the extravagant loads of amedical facility. And since this is a real life study, the financial risk was calculated.Considering a discount rate of 10% and a payback period of 20 years the Net present Valueof the cash flows generated by mounted PV array was calculated. Since the result NPV ispositive, the installation of photovoltaic is indeed a viable investment. With the help ofdrawing tools (AutoCAD 2016 for reading and extracting geometrical data from thearchitectural plans, Google Sketch Up along with the Energy Plus Plug in order to create aninput data file for the Energy Plus) as well as finding climatic data for the city ofThessaloniki (in .epw format), the simulation was performed. The results were generallypositive since the final energy consumption (including equipment and HVAC) is 183,15

kWh/m2. This consumption is lower than the average energy consumption of a Greek hotelwhich ranges from 200 to 300 kWh/m2/year and even better than some European Countries asseen in the literature review part. This amount is too huge and can not be reduced to such a

degree so that the building can be characterized as a Net-Zero Energy Hotel. Even includingRES and an efficient management of the building’s energy schedule through automatizationthe total amount of energy would, at most, reduced by 15-20 %, by inserting improvementstowards cooling loads decrease as internal shading blinds. This result can be explained, sincebuildings located in an urban environment do not, under most circumstances, have theoptions of independent power plants or enough available land mass for geothermal purposes.However, this study offers the chance to examine a realistic example and proves theimminent need for proper Energy Classification of all Hotels in Greece, as well the accuratedetection of the design flaws in already existing buildings.

Petousis Evangelos,16/12/2018

Key words: Energy Performance of Hotels, Royal Olympic Hotel, Greek Regulation forEnergy Performance of Buildings, Energy Audit, System Advisory Model, Google SketchUp, Energy Plus, Energy Simulation, Net-Zero Energy

CONTENTS

1. INTRODUCTION………………………………………………………..1-3

A. BIBLIOGRAPHIC SURVEY PART

2. STATE OF THE ART REVIEW ON ENEGY EFFICIENCY IN HOTELS

2.1. Energy consumption and demand profile in hotel industry around the world……………………………………………………………………4-12

2.2. Strategies for the design of energy-efficient hotels and nearly zero-energyhotels- Case studies of energy efficient or nearly-zero energy hotels aroundthe world………………………………………………………………….13-18

2.3. Efficient low-cost energy management techniques in hotels…………..18-22

B. EXPERIMENTAL PART

3. THE ENERGY MODELLING OF ROYAL OLYMPIC ATHENS HOTEL

3.1. Methodology description – The software used……………………………23-24

3.2. Fundamental building characteristics – Thermal zones………………….24-27

3.3. Design data…………………………………………………………………..27-28

3.4. Energy Mechanical Systems………………………………………………….. 29

3.5. Relevant climatic data of Athens…………………………………………..30-31

3.6. The creation of 3-D model of Royal Olympic Hotel………………………31-40

3.7. Energy Plus Simulation……………………………………………………. 41-46

3.8. Improvement proposals …………………………………………………….46-50

4. CONCLUSIONS………………………………………………………51-53

5. IMAGES – FIGURES – DRAWINGS APPENDIX………………...54-55

6. BIBLIOGRAPHY – REFERENCES………………………………...56-58

1. Introduction

Energy efficiency of buildings is one of the most crucial issues regarding the reduction ofenergy demand around the world. Especially in Europe, buildings are responsible for almost34 % of total energy demand across EU countries and the establishment of the obligation forNearly Zero Energy Buildings [1], both in private and public sector, has set the target ofstrong energy renovation in the existing building stock.

What is a NET ZERO ENERGY BUILDING?? The recast of the Energy Performance of Buildings Directive (EPBD) was the initial step inthe implementation of nearly-zero energy buildings in the European building stock.According to the directive, all new or totally refurbished public and private buildings wereobliged to be constructed as nearly-zero from 2019 and 2021 respectively. As described inthe directive, the definition of nZEB refers to the very high energy performance of thebuilding and the very low amount of energy required that has to be covered by energy fromrenewable sources, including renewable energy produced on-site or nearby [1]. A nZEBbuilding combines properties as greatly reduced energy demand which can be covered byenergy produced from renewable energy sources. Thus, this building is connected toinfrastructures as electricity grids, district heating and cooling systems or gas pipe network.In the cases that the energy produced is greater than the total energy demand of the building,excess electricity and heat is exported to the utility grid.

Besides the essence of this directive towards the design of buildings with net zero energybalance and the implementation of clear and specific criteria – including maximumacceptable final and primary energy use for heating and cooling or renewable energy fractionin the total primary energy used – for the majority of EU countries, Greece has yet to specifythese criteria for Greek buildings and to make clear the targets a building must achieve so asto be certified as nearly zero or net zero energy. Therefore, only general definitions are up tonow available to characterize a building as nZEB and, in order to assess if the examinedbuilding of this dissertation can be transformed into net or nearly zero, not specificassessment criteria will be used. The assessment of the studied building is based on themaximization of renewable energy fraction on the annual final energy consumption for alluses. Apart from the EPBD definitions, Torcelinni et al [2] provide a set of broad generalprinciples which outline key defining characteristics of 4 approaches to nZEB. Thesedefinitions are quoted in the below lines with their main characteristics.

1) Net Zero Site Energy: The building/site produces at least as much renewable energy asused in a year, when accounted for the building/site

2) Net Zero Source Energy: The building/site produces as much energy as used in a year,when accounted for the source. Source refers to the primary energy used to extract,process, generate and deliver the energy used to extract.

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3) Net Zero Energy Costs: In this net zero energy building form, there is equilibriumbetween the money that the building owner pays for energy services or uses throughoutthe year and the money that the utilities pay to the building owner for the renewableenergy that the building exports to the grid

4) Net Zero Energy Emissions: The building/site produces at least the same amount ofemissions free renewable energy as it uses from emission producing energy sources peryear.

The most usual forms of assessment of a net zero energy building are the forms which referto net zero site or net zero source energy. Net zero site energy refers to the final energy use,comparing the renewable energy produced per year with the annual final energy that isconsumed in the building/site for the fundamental building energy services as heating,cooling, electricity and domestic hot water. For the purposes of this dissertation, thedefinition of net zero site energy will be used as reference base in order to assess if theexamined building can be transformed into net zero or nearly zero. In Greece, apart from residential buildings, buildings in tertiary sector present strong enoughcontribution in the total energy demand of Greek buildings. This dissertation aims toinvestigate into the effect of hotel buildings in the total energy consumption of Greekbuildings and to propose the exact ways in which this effect can be minimized. Morespecifically, after quoting in literature review chapter the fundamental energy profile thatcharacterizes hotels in Greece and abroad, a luxurious 5-star hotel building will be analyzedthrough Energy-Plus simulation in order to investigate the potential of retrofitting thisbuilding into net zero.

Tourism sector, including hotel buildings, is one of the most profitable and exportablesectors of Greek economy, contributing to approximately 16 % in the Greek GDP [4].Furthermore, the environmental aspect of hotel industry around the world is quite significantsince this type of industry contributes to 5 % of global CO2 emissions. Apart from these, hotelbuildings operate 24 hours per day and the operational profile of the various thermal zones -such as rooms, restaurants, lobbies, swimming pool and all the remaining operating places- isquite different, leading to discrepancies in the energy profile and the energy demand betweenthem. Tourists have to be satisfied from the whole hotel operation, including thermalcomfort. All thermal comfort parameters related to energy consumption have to be monitoredcontinuously in order to ensure thermal comfort in all the operating places in parallel with theminimization of total energy consumption. Given all the above, it is extracted that the issueof minimizing the energy demand of hotel industry is of high enough importance for varioussocial, economic and environmental reasons.

The energy consumption in hotel industry is affected by a wide variety of functionalparameters. Climatic conditions, usually expressed in terms of Heating and Cooling DegreeDays, the total hotel floor area and the number of guests are three factors that are consideredto have a considerable effect in energy profile of hotels, as analyzed in the literature reviewpart of the dissertation. What is more, the thermal efficiency of building envelopecharacteristics, the efficiency of energy systems used for heating, cooling, DHW and

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electricity purposes, the presence of hotel facilities as conference centers, spa and poofacilities, food covers or guest-nights sold (occupancy) are factors that should beimplemented in a holistic approach for energy conservation in hotels [17]. It is necessary tobe noted that smart management systems that are applied in hotel industry by hotel managersare also a crucial factor that affects significantly the energy conservation potential in thisspecific type of buildings. In the literature review part, there are quoted some cases of hotelsthat have implemented smart energy techniques in order to reduce the overall energy use. After this dissertation, typical energy profiles by which a wide range of hotels around theworld in various climates is characterized will be identified, as well as the main strategiesthat are already implemented in hotels towards low-energy management design and operationof hotels, by quoting several case studies. Moreover, by the simulation of a luxurious 5-starhotel, the potential of retrofitting the hotel into net zero will be identified. In summary, thisdissertation aims to investigate and give the relative answers in issues as the followings.

1) Energy profile of hotels – The study of distribution of energy consumption in hotels peruse

2) Literature review on the quantitative effect of various physical and operationalparameters in total hotel energy consumption, in final and primary energy terms

3) Report on existing Net Zero Energy Hotels and smart energy management techniquesthat can be applied in hotel industry in order to minimize the energy waste

4) Energy simulation through Google Sketchup and EnergyPlus softwares of Royal OlympicHotel in Athens

5) Report about exporting results related to energy consumption of the examined hotel andproviding solutions towards the possibility of transforming it to net zero

6) Simple financial feasibility analysis of these energy renovation proposals

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A. BIBLIOGRAPHIC SURVEY PART

2. State of the art review on energy efficiency of hotels

2.1. Basic characteristics of energy consumption and demand of hotels – Energy profile of hotels in different climates around the world- Historical data

Hotels are the most energy consuming buildings across tertiary sector due to theiroperational characteristics and large discrepancies between their operational profile can benoted, giving the initial impression that their energy consumption pattern is difficult to bediversified. Main factors influencing energy consumption in hotels are physical like climaticcharacteristics (temperature, solar radiation, humidity) or energy systems and operationalfactors as occupation patterns and operational practices for laundries, swimming pools,restaurants and conference rooms. For this reason, there have been many scientific efforts toidentify the energy use in hotels around the world. According to 2012 surveys, it wascalculated that there are 300,000 hotels worldwide and 70 % of them are located in Europeand North America. A typical distribution globally of energy consumption in hotels per eachuse can be seen in the below figure.

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Hot W

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Spac

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Light

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Cook

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Office

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15%

20%

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30%

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Figure 1. Typical distribution of energy consumption in hospitality sector per use [5]

About Europe, it has been estimated that the annual average energy use among Europeanhotels ranges between 239 and 300 kWh/m2, 50 % of which is attributed to electricity, and

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hotel sector in Europe has been estimated to account for almost 0.7-1 % to the final energyconsumption of buildings in Europe [5].

Indicatively, from the same survey for European countries, it is quoted that the approximateannual energy consumption values are 215 kWh/m2 for Italy, 273 kWh/m2 for Greece, 278kWh/m2 for Spain and 420 kWh/m2 for France [5]. Additionally, for United Kingdom, theannual absolute energy use for typical holiday hotels is equal to 540 kWh/m2, in which 400kWh/m2 is fossil fuel consumption and the remaining 140 for electricity, and for best practiceholiday hotels 360 kWh/m2 (280 for fossil fuels and 80 for electricity consumed). For Greece, several papers have been published, trying to identify the energy profile ofGreek hotel sector. The results yielded by these papers present some disagreements betweenthem. The case-study for the energy classification of Greek hotels, in which the above resultswere based, reports an average annual energy consumption of 273 kWh/m2, based on asurvey of operational energy data on 158 hotels, accounting for 4.3 – 5 % of total finalenergy consumption of Greek buildings, while according to CRES surveys, hotels consumeon average 407 kWh/m2/year, accounting for 10 % of total primary energy consumption,even Greek hotels represent only 0.82 % of the total building stock [6]. The main reason forthese disagreements is focused on the different sample of the surveys and the differentoperational parameters that are considered to affect the extracted energy profile results.Initially, the energy consumption per use for Greek hotels is depicted in the following figure2.

About the survey conducted in 158 hotels, energy measures could be done in 90 of them. 90Greek hotels were clustered into 5 energy classes, by identifying the normalized thermal andelectricity consumption taking into consideration size and climatic normalization, as well ascumulative frequency distribution analysis. All hotels were located in Greek climatic zonesA, B, C, because of lack of availability of hotels in zone D and 54 % of them operatethroughout all the year, while the remaining operates seasonally.

72%

9%4%

15%

Heating Lighting

Cooling Electric Appliances

Figure 2. Annual energy consumption per use in 158 Greek hotels [5]

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From the above figure, the dominant percentage for heating needs can be explained mainlybecause of the poor thermal efficiency of the building envelope and the use of conventionalnon-efficient heating systems. It is characteristic that 40 % of the hotels of the sample havebeen constructed before 1979 when there was lack of any obligation for thermal insulation ofbuildings. The limited use of RES, with an exception of Domestic Hot Water via solarcollectors, and the non-existence of BMS systems connected to the central heating or coolingsystems in 52 % of hotels examined shows that the sample chosen had a great potential inenergy-efficiency measures.

The results of the survey conducted reported a normalized annual electricity consumptionequal to 140 kWh/m2 for typical hotel buildings, which were the 50 % of the sample, and 58kWh/m2 for the best practice buildings, which were the 25 % of the sample examined. Aboutthe normalized annual oil consumption, for typical hotel building, it was estimated to 28kWh/m2 and for best practice buildings 11 kWh/m2 [5].

Apart from the poor efficiency of thermal envelope which leads to big thermal losses, thelack of innovative efficient building systems, which can replace existing oil-fired non-efficient systems, and energy management systems in the dominant majority of the hotelsleads to great energy losses and big operational and energy costs. The average electricity andthermal energy consumption of the hotels of the sample has been estimated approximately to290 kWh/m2/year for hotels with annual operation and 200 kWh/m2 for hotels with seasonaloperation [5]. Furthermore, 50 % of the examined hotels consume annually electricity above140 kWh/m2 when the annual electricity consumption in best practice buildings does notovercome 58 kWh/m2.

Given the results of the survey, hotels are a rather consuming building category in energyterms. Apart from heating, electricity is one main sector in hotels with high energyconsumption, due to the electricity need for the operation of restaurants, laundries and theremaining hotel spaces, and this trend for increased electricity consumption is enhancedespecially during summer seasons for cooling needs because of the use of air-conditioningsystems. The use of RES for electricity production, as well as of BMS systems for the bettercontrol of heating, cooling and electricity consumption, are fundamental prerequisites for thestrong energy refurbishment of the hotel building stock, towards their transformation into netzero energy buildings. The following figure depicts the strong energy potential of Greekhotels.

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050

100150200250300350400450

407

250

187152

92

Figure 3. Tertiary sector in Greece - Average annual energy consumption per building category(kWh/m2/yr) [5]

About the use of RES in hotels, it is interesting to quote some elements about the evolutionand the features of the use of solar systems in Greek hotels, both for heating and DHW. Theuse of solar-combi systems is not extensive in the hotel sector, since the majority of hotelsoperates seasonally, the heating period is short and, the most important, in South Europeheating systems with convective or radiative heating elements require medium and hightemperatures – at least 55 ° C which solar systems cannot deliver efficiently during wintermonths – while underfloor heating systems need to operate in at least 40 ° C [4].

A survey conducted in 2014 evaluated the use and perspectives of solar systems in Greekhotel sector by monitoring 69 hotels. In this sample, 73.9 % of them are 5* or 4* hotels. Themain installed solar collectors features in the sample referred are presented in the belowfigures.

Figure 4. Installed collector’s area per bed [4]

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Figure 5. Installed hot water storage vessel capacity per collector’s area [4]

As it can be seen in figure 4, the majority of hotels present solar collectors surface less than1 m2/bed. The use of high efficient solar systems has led to the decrease in the needed surfaceof the collectors per bed. In addition, more research should be done regarding the correlationof hotel type (5-star, 4-star etc.) and installed collector’s area per bed.

On the contrary, figure 5 reveals that 40 % of hotels examined use hot water storage vesselwhich have capacity less than 40 lt/m2 of solar collector. This figure reveals that there is atrend for under-dimensioning the capacity of storage vessels, leading to the lower efficiencyof solar systems since they do not operate at their full potential. Moreover, the chance ofstagnation temperatures is more frequent through the under-dimensioning of storage vessels.This is not the appropriate design for the hot water storage vessel since it can lead indifficulties regarding the peak demand covering in sea-side seasonal hotels, where most ofthe entire hot water demand occurs over a period of two hours in the evening. For all theabove reasons, the design of storage vessels in solar systems requires the avoidance of under-dimensioning.

Moreover, an important step to this purpose is to identify the parameters that are most highlycorrelated to the hotels energy consumption. In a survey made in 1999 by Australiangovernment and a research in 29 hotels in Singapore in which exponential regression modelanalysis was used, the correlation between monthly electricity consumption and occupancyrate was proven low, in levels of R2 equal to 0.5 [11]. On the contrary, a Hong Kong study in16 hotels in which monthly electricity consumption was tried to be associated with monthlynumber of guests and monthly mean outdoor temperature revealed that temperature effect isfour times greater than occupancy effect. These two surveys stated that the occupancy rate ofhotels has little effect on the energy consumption profile of hotels.

Additionally, in other surveys conducted such as in 200 Taiwan hotels [13], multipleregression analysis revealed that both number of guest rooms and gross floor area explain91.2 % of the annual variation of energy consumption. In many surveys conducted, is hasbeen noted that climatic parameters have not been included as influencing factors to theenergy profile analysis. However, monthly weather data are fundamental elements of suchthis analysis and help identifying more rapidly malpractices, operational mistakes and energy

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inefficiencies in energy profile of hotels. It is underlined that the operation of HVACsystems, which account for 50 % to the electricity consumption of hotels in tropical areas, isbased on outdoor weather conditions. Therefore, the insertion of weather data in energymodelling of hotels is a basic prerequisite to the implementation of smart energymanagement systems towards the enhancement of energy efficiency of hotel industry.

In general, when trying to identify the most major factors that affect energy consumption inhotel sector by using regression analysis models, usually there are more than one parametersthat affect statistically significantly the energy use. The energy and water use in hotels shouldbe diversified across different energy forms in order to find more exact and clear patterns ofcorrelation. For example, in a survey conducted in 36 Hong Kong hotels [16] the energy usewas diversified into water, gas, diesel and electricity consumption and the operationalparameters considered to affect energy use were the Gross Floor Area, annual total number ofGuestrooms (Guest) and annual total number of food covers (FC). For each one of the latterenergy uses, the survey adopted the following principles:

- Water use data from hotels was studied separately for hotels with in-house laundry andhotels without in-house laundry

- Regarding gas use data, hotels with gas-fired boilers were studied separately fromrespective with non-gas boilers. The same approach was used also for diesel consumption

- Electricity use data was used separately for hotels with electric water heating and hotelswithout electrical water heating

For each one of the above energy use categories, the following conclusions were extracted.

a) Water consumption - For hotels without an in-house laundry, where the most of water useis by guests or in the kitchen, the product of Guest and FC, as well the product of Guest,FC and m2 gave a high correlation of coefficient, approximately equal to 0.95. On thecontrary, for hotels with an in-laundry, the maximum R2 was found to be 0.55 for allcombinations of parameters examined, because the lack of laundry washing data couldnot lead to a satisfactory coefficient of correlation.

b) Gas consumption – Only in the case of hotels with gas-fired boilers there is sense toexamining gas uses correlation with the above operational parameters. In this hotelcategory, in which hot water and heating needs cover the 75 % of gas use, includingguestrooms, laundries, kitchen and the remaining operational spaces of the hotel, gas useis strongly associated with size of the building in terms of GFA. The correlation betweengas consumption and m2 of gross floor area is expressed by R2 equal to 0.865 [16]. Grossfloor area is the only factor that affects statistically significant gas consumption. Whendiesel is used in hotels for heating and hot water needs, similar conclusions have beenextracted regarding the correlation between diesel use and GFA.

c) Electricity consumption – For hotels using electricity for heating or hot water needs, thesame trend with gas use is repeated since the main explanatory factor is either GFA with

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a correlation of R2 equal to 0.87 or the product of GFA and number of guestrooms whichgives R2 equal to approximately 0.9. Again, for non-electrical water heating hotels, thecorrelation between electricity use and number of guestrooms or gross floor area is weak,since electricity consumption is independent of parameters related to the size of thebuilding or to the space heating or hot water needs of guestrooms. Attention should begiven in electricity, since electricity can be diversified in various areas and engineeringsystems, especially in hotels. For example, the further breakdown of total electricity useby different functional areas as guest floors or by engineering systems as air conditioningunits should be widely proceeded in order to identify various correlation patterns ofelectricity with a wide range of different type of parameters.

In general, as extracted above, energy use involving hot water, whether by electricity, gas ordiesel, can be sufficiently explained by GFA on a hotel building. However, a negative pointin this survey is the lack of climatic data in the regression analysis. Since HVAC operationand energy consumption is definitely dependent on outdoor temperature, humidity and solarradiation, the inclusion of these data as explanatory indicators in the above analysis couldfurther examine the strength of correlation between various energy uses. It is reminded thataccurate regression models must include all parameters that have been considered by theoryand literature as affecting factors to the dependent variable.

In a survey conducted in Hilton International Group hotels in Europe [12], almost the sameconclusions were extracted regarding the effect of parameters as total floor area, services andfacilities, number of guests and food covers. Moreover, in this paper there was a greatereffort to quantify the effect of climatic parameters in energy and water use of a hotel. Themost remarkable conclusions are quoted below.

a) Total hotel floor area: As shown in the figure 7, the correlation between annual energyconsumption and total hotel floor area is high with R2 greater than 0.7, as expected.

b) Services and facilities: Such services as pools, spa, health clubs usually affect the energyconsumption of hotels, especially in cases of upscale luxury hotels which use energy-intensive systems for these facilities. Although, in this survey, Hilton hotels thesefacilities did not show to have direct and essential effect in energy consumption.Moreover, they have the trend to reduce the correlation between water consumptionversus floor area and floor area did not seem to be a crucial factor for water use in hotelswith water-base activities.

c) Climate: Since space conditioning account for almost 50 % of total energy use in hotels,it is obvious that the implementation of parameters as mean outdoor temperature, solarradiation or relative humidity play such a significant role in the energy profile of anyhotel. From the other hand, the location of hotels in many surveys in non-distinctiveregions and the large variety of additional services in hotels could lead in coefficients R2

lower than expected, as in this survey. For instance, R2 was calculated 0.48-0.95 for totalenergy use and equal to 0.51-0.97 for space conditioning energy [12]. It is alsoremarkable that R2 was found constantly greater than 0.7 in hotels located in colderclimates. Nowadays, the incorporation of parameters as Heating Degree-Days and

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Cooling Degree-Days permitted the adjustment of space conditioning energy to climaticparameters and the development of more accurate resource consumption models. R2

between energy consumption and HDD or CDD usually reaches values upper than 0.75 or0.8 in studies which quantify the energy use in hotels among various physical andoperational parameters.

d) Guest-nights sold: Figure 8 depicts the relationship between energy consumption andguest-nights sold. Regarding to respective water consumption, again the presence of pooland spa facilities reduces the strength or relationship between water consumption andnumber of guests. This trend is by far more obvious in upscale hotels which include thesefacilities, in which R2 coefficient between annual water consumption and guest-nightsolds is reduced from 0.63 to 0.27 if pool and spa facilities are included.

e) Food covers served: Since it is estimated that food cover served requires 4-6 kWh ofenergy and 35-45 l of water, it is expected to be a decisive factor, explaining energy andwater consumption. R2 is almost 0.65 for both energy and water consumption, even inupscale hotels this coefficient is by 30 % reduced [12]. It is observed that coefficientcorrelations are in general weaker in upscale hotels, since in these hotels luxuriousfacilities as pool/spa or sport facilities have biggest share in the total energy profile andthe total energy profile of these hotels consist of a lot of different end-uses and ischaracterized by greater heterogeneity among different hotels. Hence, it is more difficultto identify typical average energy profile for upscale luxurious hotels than in the case ofmid-market hotels [12].

Despite the various physical and operational parameters included in all the above surveys,factors as conference center capacities, requirements of conference rooms, actual number ofconference participants, water volume flows at pool/spa facilities, number of daily guestsusing health facilities and maintenance of mechanical building systems should be included inthe scientific analysis of energy profile of hotels. Towards this direction, the subclassificationof hotels with similar characteristics regarding their provided facilities and services intospecialized groups could be a better solution regarding the establishment of a more precisehotel resource consumption model. It is finally suggested that upscale hotels should beindividually audited about their energy profile, because of the high heterogeneity that theyoften present in their energy and water consumption, as proven in the previous analysisreferred.

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Figure 6. Relationship between total annual energy and water consumption versus total hotel floor area

Figure 7. Relationship between total annual energy and water consumption versus annual guest-nightssold

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2.2. Strategies for the design of energy-efficient hotels and nearly zero-energyhotels- Case studies of energy efficient or nearly-zero energy hotels aroundthe world

Α) Boutiquehotel Stadhalle – Vienna, Austria

The first hotel example, located in urban environment, that achieved the goal of Nearly ZeroEnergy (neZEH), is Boutiquehotel Stadhalle, which is built in Vienna. Having the oldbuilding already being renovated from 2001, the construction of a new building according toPassive House Standard contributed to the strong minimization of hotel energy consumptionand the adoption of environmentally friendly practices for the purpose of a wholemanagement strategy focused on the minimization of the environmental impact before theimplementation of European Directives for the Energy in Buildings. The total refurbishmentof the hotel was ready in 2010.

Image 1. Boutiquehotel Stadhalle – Nearly Zero Energy Hotel in Vienna, Austria [19]

More specifically, after the implementation of the new passive house building, there were41 guestrooms on the old building and 38 in the passive building with a total floor area equalto 2.271 m2. Additionally, while the old renovated building used district heating and nocooling or ventilation system existed, in the new passive building a groundwater heat pumpwas used for heating and cooling with controlled air room ventilation. Ventilation system hasheat recovery ability with 90 % efficiency. The heat pump makes exploitation of a 13 kWpeak PV system, with total roof area 93 m2, which generates the energy needed for theoperation of heat pump. Photovoltaic panels contribute to the partial coverage of electricity

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needed for groundwater heat pump, lighting and appliances, apart from the electricity derivedfrom electricity grid. Furthermore, 130 m2 of solar thermal panels produce Domestic HotWater, which aims to pre-heat the fresh air through the ventilation systems [19].

Finally, as for renewable energy systems used in Boutiquehotel Stadhalle, the aim of themanager and the owner of the hotel is to install 3 wind turbines in the roof for even greaterelectricity production, waiting for the permission of the authorities to do so. One morepractice of smart management applied in the hotel is the implementation of BuildingAutomation and Control System, which is constantly and continuously checking andregulates energy used for heating, cooling or ventilation based on real energy demand orpreset schedules. The energy profile and energy consumption per use, as the result of thedesign which incorporates all the above energy systems, is depicted in the below table.

Table 1. Average annual energy consumption – Annual primary energy consumption for BoutiquehotelStadhalle [19]

As depicted above, the annual primary energy consumption for passive building is equal to108 kWh/m2. This energy consumption value is in partial accordance with reference values,as defined in neZEH project for Western Europe Countries [19].

As analyzed, the main objective of hotel owners and managers was to make a hotel buildingin line with nowadays trends of passive house and principles adopted in Nearly Zero EnergyHotels. Apart from their main goal of strong minimization of energy used for the coverage ofheating, cooling, DHW, electricity and ventilation needs, they adopted a total environmentalstrategy with the purpose of propagating the implementation of smart hotel managementtechniques which reduce the environmental impact. It is worth to quote that hotel managerand owner arranges regular informing of guests regarding the adoption of green energypractices that led the hotel to become net zero, provide 10 % discount to guests coming bybike or train due to the use of low emissions means of transport and, finally, haveimplemented by 90 % the use of LED lighting as well as water saving measures as theinstallation of cisterns to store rainwater and exploit it for toilets and garden.

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Β) Nearly Zero Energy Hotel in island of Gozo – Malta

The first case study of hotel transformed into net-zero energy belongs to the island of Gozo,in Malta. Malta is characterized by mild, moderate temperatures during winter and hotsummer season, with a typical summer temperature reaching 33 ° C in early afternoon andsolar irradiation levels reaching 1,875 kWh/m²/year, making Malta the sunniest climate inEurope. The examined building is a 3-star hotel building with 4 floors and a total conditionedfloor area 397.3 m2 and total floor are equal to 737.3 m2.

In the construction phase, regarding the building envelope it was chosen U-values ofexternal walls and roofs to be 0.16 and 0.34 W/m2K, together with low-e double glazed air-filled windows, which had a U-value equal to 3.1 W/m2K. The initial simulation, usingDesign Builder software, reported that the optimal heating and cooling design capacity was21.13 and 20.49 KW respectively. After the design and construction phase, the initial energyprofile of the hotel was the following.

Figure 8. Initial energy profile of Gozo hotel [9]

It is extracted from the above figure that, due to the mild heating season in countries asMalts and the construction of building envelope, space heating is much lower compared tothe remaining energy needs of the building. It is understood that specific measures had to betaken in order to modify the lighting and water heating consumption.

Regarding lighting, apart from common solutions as occupancy sensors, advanced LEDlighting systems had to be used, combined with smart daylighting solutions. Theimplementation of solar tube, which brings natural light inside and keeps heat out of thebuilding, and the use of Parans optical fiber system which consists of tracking solarconcentrators set at roof level and connected through optical fiber cables to the indoor units

15

are the indicative solutions to the lighting problem of the building. The combination of thetwo referred above solutions leads to the reduction of electricity consumption for lightingequal to 50 % [9]. Additionally, these systems are cost-effective due to their low cost andinsert natural light into the building, improving deeply the quality of internal lighting andproviding a good spectrum natural lighting for most of the year.

Regarding domestic how water and space cooling needs, the introduction of geothermal heatpumps or solar cooling applications met practical difficulties. For this purpose, it waspreferred to install a solar photovoltaic system combined with high efficiency solar-readyheat pumps instead of a solar heating system, since it offers less piping works, pumps andwater storage tank and, therefore, it requires much less maintenance.

Before assessing the effect of these measures in the transformation of the building into netzero, it is advisable to quote the exact definition of Energy Performance Certificate Ratingfor Malta [9]. EPC Rating is defined as the percentage of the carbon emissions of the hotelcompared to the same hotel but built using reference (minimum) specifications, as set by theminimum energy requirements for Maltese buildings, plus 20% improvement. According tothe Maltese criteria for energy performance of buildings, this specific building belonged toEnergy Class B before the interventions and was led to class A after the interventions, sinceEPC rating dropped from 85 to 47. In addition, Cost-Optimal Study for Maltese near-zeroenergy buildings has produced an EPC primary energy rating equal to 40 kWh/m2/year forresidential buildings and 60 for non-residential building, so the examined building which hasan EPC primary energy rating equal to 59 kWh/m2/year fulfill the criteria of cost-efficient,near-zero energy building [9]. Attention should be given in the fact that the characterizationof the building as nearly zero was given based on the Net-Zero Source Energy Buildingdefinition.

C) Net Zero Energy Tourist Village in Alexandria, Egypt

The design of net zero energy hotels and tourist attractive places is the accurateincorporation of renewable energy sources and the identification of the appropriatecombination of RES in the whole energy profile. In the present case, a tourist village inAlexandria, Egypt, which is characterized by a capacity of 1000 guests and 350 bedroomswas examined regarding the renewable energy incorporation in order this tourist village to bedefined as net zero energy. Initially, the scaled total annual energy consumption of this touristvillage is 3650 MWh with a peak of load demand around 1008 kWh during the summerseason [15].

Several configurations including PV photovoltaics, wind turbines and diesel generatorswere examined regarding their levelized cost of energy (COE) and their net present cost(NPC) so as to assess the optimal configuration that would lead to the minimization of netpresent cost and GHG emissions of the tourist village in order the latter to be characterized asa net zero- energy and environmentally-friendly village. According to the analysis conducted,the optimal configuration of RES included was the following.

a) PV panels – total capacity 1600 kW, capacity factor 34 %, levelized COE 0.0595 $/kWh

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b) Wind turbines – total capacity 1000 Kw, capacity factor 27.317 %, levelized COE 0.0752$/kWh

c) Diesel generator – total capacity 200 kW – total amount of fuel consumed 11,570 L/year,marginal generation cost of diesel generator 0.06 $/kWh

d) Power converters – total capacity 1000 Kw – time of annual operation 7728 he) 2000 batteries, capacity of 589 Ah each – expected lifetime of batteries 17.26 years

In the below figures, the contribution of the cost of each one of the components to the abovereferred optimal configuration is quoted, as well as the monthly electricity consumptionproduction from the different components. All data results were extracted by using as annualinterest rate 8 % and project lifetime equal to 25 years.

PV Wind Batteries ConverterDiesel Generator0.00%

5.00%

10.00%

15.00%

20.00%

25.00%

30.00%

35.00%

Figure 9. Cost of each component to the optimal Hybrid Res configuration [15]

Figure 10. Monthly electricity production for optimal hybrid system components [15]

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The resulted levelized COE of this system is 0.17 $/kWh, the total NPC equal to 15,383,360$ and the maximum renewable fraction is 99.1 % achieving a zero-energy sustainable touristvillage [15]. In addition, GHG emissions emitted from the optimal hybrid RES configurationis only 31,289 kg/year, an amount negligible if compared to other systems configurations.The excess electricity from RES production can be used by dump loads in form of heating orcooling loads, increasing further the hybrid system efficiency and decreasing COE less than0.17 $/kWh. Finally, the high efficiency of this optimal HRES system is proven by theachieved capacity shortage which is 0 % and the unmet load, which is the electrical load thatthe power system is unable to serve and it occurs when electric demand is greater than therespective supply, which is too 0 %.

2.3. Efficient low-cost energy management techniques in hotels

A) Monitoring and forecasting daily electricity consumption in hotel sector

Up to some years before, the widespread conception was that the efficiency of advancedenergy systems in hotels was suffice for the strong reduction of energy and operational costs.It is characteristic that, before a decade, reliable energy management systems were not usedin 90 % of global hotels and accurate control of various energy uses was not possible [11]. Inaddition, the low education of hotel staff regarding smart energy management techniques wasone more constraint in the implementation of low-cost techniques for the monitoring andcontrol of energy consumption patterns. In fact, the two main ways to maximize energyefficiency in hotel sector are the two following.

a) The development of forecasting techniques which can produce forecasts about the energyconsumption patterns, combining all the relevant factors as weather and occupation data,as well as monitoring techniques about the control of different energy facilities

b) The implementation of more automatic control systems and more efficient technologies

Since the first solution seems to be the least expensive and the need to develop the skills ofthe hotel staff to interpret energy-consumption data and to identify energy savingopportunities is more than apparent, monitoring and forecasting energy patterns should be thefirst priority in hotel sector. In addition, the high operational cost for energy has led severalhotel owners to search for smart management techniques.

The current subsection aims to present the main figures that prove the absence offorecasting electricity techniques in these 2 Cuban hotels. Electricity is one of the most majorenergy uses, contributing to power in several cases HVAC and lighting systems, as well asoperational needs of spaces as restaurants, kitchens and conference rooms. In tropical andsubtropical areas as Cuba, electricity fraction in energy costs is 60-70 % and HVACcontribution to this electricity consumption can be up to 50 % [11]. Therefore, special focushas to be given to the development of monitoring and forecasting electricity consumptiontechniques, as well as to the improvement of operational practices by educating hotelpersonnel to use appropriately the implemented tools.

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In the present case of the 2 hotels examined, from which hotel A is beach hotel with 222rooms and hotel B is a city hotel with 49 rooms, the main point of analysis is the comparisonbetween the forecasted and actual electricity consumption by using daily control electricitygraphs as reported below. Initially, the comparison made in monthly basis revealeddiscrepancies between the forecasts and actual situation, leading to the conclusion that a moreappropriate energy performance indicator is needed which has to be a function of theoperational data usually handled by the hotel staff and in parallel to be simple so as to avoidpractical difficulties in its implementation. For this reason, the Room Degree Day (RDD) wasintroduced, combining the effects of cooling degree days (CDD) and hotel occupation, andthe chosen Energy Performance Indicator used was an efficiency factor between electricityconsumption and RDD [11].

The correlation of electricity consumption and RDD is high, with R2 upper than 0.75 inmonthly data terms. In the below figures that contain daily electricity consumption data forJanuary, extracted from data taken between 2011-2012 for all months of the year as afunction of RDD constructing Energy Baseline figure, Goal Baseline is developed bycorrelating the points below the EnB, which represent the most efficient points of the hoteloperation. Points above EnB are signs of inefficient operation, mainly because ofmalpractices of the staff. The main reasons for these inefficiencies are focused on incorrectoperation of HVAC systems in restaurants and conference rooms, inadequate use of electricovens in the kitchen and little control on the on-off timing of exterior lighting. Thecorrelation between electricity consumption and RDD in daily terms is quite high, with R2

equal to 0.75 for EnB and 0.9 for GB. In the following figures, the maximum efficiencycomes at the points close to the GB straight line.

Figure 11. Daily EnBs and GBs for January [11]

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Apart from the correlations and the figures referred to the daily energy consumption andRDD, daily control graphs were implemented in order to identify quickly energyinefficiencies in daily basis. These graphs were induced to quote variations between dailyelectricity consumption and RDD, comparing again Energy Baseline and Goal Baselinecurves in order to detect discrepancies between the actual and desired energy consumption.12 daily control graphs were made for each one of 12 months, extracting the exactrelationship between electricity consumption and RDD.

Figure 12. Daily control graphs for January [11]

B) The effect of staff behavior change in hotel sector energy profile

An analysis made in a case hotel located in Qatar proved that, apart from refurbishmentsrelated to building envelope, energy systems and the survey into the quantitative effect ofvarious physical and operational parameters referred above, the behavior of the staff in orderto avoid unnecessary use of energy is also of quite importance towards a more sustainableand energy efficient hotel sector. In general, remarkable examples of a more sustainable staffmanagement of hotel resources are reusing towels, using sensors for the control of lighting orHVAC systems in the absence of clients from their guestrooms or using equipment onlywhen needed.

In this hotel case studied in Doha of Qatar, it was estimated that the refurbishment of thebuilding envelope could lead in the best design case in a reduction of total energy site usedequal to 7.5 %. It is easy to understand that this reduction can be further increased, since in aquite hot and dry climate as this of Middle East, only interventions in envelope design don΄tgive a requested remarkable result. Indeed, if a behavior change demand scenario isimplemented in the calculations, it will lead in approximately 5-25 % energy conservation.Hence, it is obvious that these two scenarios have to be merged and included both in thesimulated energy renovation of hotel as depicted in the below figures [14].

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If these two solutions are used both, then they can lead to maximum energy savings up to 24% and to a reduction in electricity consumption up to 22%. Moreover, the incorporation ofrenewable energy generation in the energy mixture of the hotel is quite significant from theenvironmental aspect, since energy produced from renewable energy sources usually reducesthe CO2 emissions. In the current case, the implementation of the two above solutions fromdemand side and the incorporation 30 % renewable energy produced from the supplyscenario side, with wind and PV electricity generation, can lead to the achievement of 41.4 %reducted emissions [14]. The below figure describes the annual CO2 emissions in all thescenarios involved, as reference case scenario, best design alternative scenario with 15 %incorporation of behavior change and the scenario which involves the participation ofrenewable sources energy generation.

giv

Figure 13. Annual CO2 emissions in various examined scenarios [14]

In general, the above energy management strategies show the map for the implementation ofenergy conservation practices in hotel industry. In the analysis quoted below, an attempt topresent these practices that should be followed from hotel managers is given.

Firstly, rational use of energy in hotels require the establishment of a management standardwhich follow the principles of PDCA cycle [20]. The planning phase which includes theidentification of the most significant points of energy conservation programs, the do phase inwhich the planning programs are implemented including education and training of the hotelstaff, the check phase in which there is assessment and verification of effects of energyconservation practices and the action phase, which includes the review of the managementstandard and the planning program, are the most important parts of this PDCA cycle.Moreover, some of the most dominant energy saving practices are the following.

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- Energy conservation during guest room cleaning: in guest rooms, including the turning-off of fan coils and leaving natural lighting to get in the room without the need of turningon electrical lighting

- Ventilation of fan control in kitchen spaces: Since there is big potential on energyconservation in fan operation, fan operation time should be restricted in short values.

- The establishment of manuals about energy conservation practices in each hoteldepartment: Documented manuals of energy conservation practices should be easilyobserved in staff and guests in each one of guest room service, banquet service and foodand drink department.

Apart from the above, there are several measures that hotel managers can implement in thetotal hotel management in order to establish an accurate management system and persuadetheir staff to follow this system, including energy conservation practices. Among others,significant measures that managers should include in their management are the following. Itis noted that the following recommended measures explain some of the most usual technical

- Rationalization of combustion: Since boilers are often used for hot water or heatingneeds, a standard air ratio, valued in the range 1.2-1.3, should be set for making theenergy use of combustion rational. This can be achieved through the adjustment of theboiler setting during its periodical inspection [20].

- Prevention of steam heat loss: Since approximately 20 % of produced steam is lost,maintenance and inspection of steam traps and accurate insulation of steam valves can beeffective solutions regarding the reduction of steam waste and can lead to significantenergy conservation potential

- Balance of air-intake and exhaust in kitchen area: Keeping the inside air pressure slightlynegative in kitchen rooms is suggested in order to prevent the odor leaking from kitchento outside. Although, in many cases this pressure becomes strongly negative, affectingconditioned air in the whole dining area or entire the hotel in which the air pressurebecomes strongly negative. In order to keep the necessary balance between air-intake andexhaust, the prevention of operating fan more than needed is necessary.

- Air-conditioning control for banquet halls: Since banquet halls in hotels are placescharacterized by intense people concentration, their heating and cooling energy needs areintense throughout the whole year, especially for hotels located in urban areas. In thiscase, a wide variety of hotels have implemented a 4-pipe air-conditioning system whichcan produce a remarkable amount of energy loss, especially in the case that heating andcooling operation are operated in same time, causing ΄΄mixing loss΄΄. The establishmentof setting proper temperatures in heating and cooling operation and the simultaneousaccurate maintenance and regular inspection of automation control systems, in orderheating and cooling mode not to be simultaneously operated, are fundamentalprerequisites as energy conservation measures in many hotel enterprises [20].

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Β. EXPERIMENTAL PART

3. THE ENERGY MODELLING OF ROYAL OLYMPIC HOTEL

3.1. Methodology description – The software used

The hotel that was chosen to be assessed regarding its energy performance is RoyalOlympic, in the center of Athens. The hotel was designed through Google Sketchup softwarein order to be exported in Energy Plus software. With this procedure, energy performance ofthe hotel was analyzed and the main conclusions are presented in the following sections. Themain sources of information for this analysis were the architectural Autocad designs of thehotel, climatic data of Athens city, as well as thermal, cooling and electrical loads that werecalculated through Energy Plus software and were based on design data inserted in theprogram, according to Greek energy standards (technical guidelines of Energy Regulationsfor Building Energy Performance) [31].

More specifically, regarding the energy modelling of the building, Royal Olympic hotelconsists of 6 main floors and the ground floor in which services as lobby, restaurant,conference room are hosted. Due to the high complexity of the Royal Olympic hotel building,emphasis was given separately for the coverage of basic energy needs of guests for heating,cooling, domestic hot water, electricity and separately for facilities. In this scope, initially atypical guest floor was modelled in the above mentioned softwares regarding its energyconsumption and its energy efficiency and the results were generalized in order to extract therequested results for the whole building.

The main steps that were followed based on the above procedure, aiming at the final energyassessment of the hotel building are the following.

1) The creation and the drawing of typical floors in Sketchup Model

2) The separation of the typical studied floor in thermal zones

3) An energy simulation tool, including geometry of building, insulation, internal and designloads, energy systems was used in order to calculate the minimum energy needs of thebuilding

4) The calculation of final and primary energy consumption of the hotel building

5) The energy assessment of the hotel building, taking into consideration the average energyconsumption in Greek hotels, as stated and referred in the literature review part of thisthesis

6) The implementation of energy saving measures, if needed, in order to improve the energyefficiency of the building and the examination of the financial feasibility of thesemeasures, taking into account NPV criteria or payback period

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7) The final question that has to be answered is if Royal Olympic hotel can achieve thetarget of nearly zero energy building and in which percentage this target can be fulfilled

3.2. Fundamental building characteristics – Thermal zones

As referred above, Royal Olympic hotel building is located in the center of Athens. Itconsists of three main guest floor buildings, each one of which contains 6 floors. For thesimplification of the modelization and the energy consumption calculation procedure, a guestfloor approach was considered to be applied. According to that, in each one of the 3buildings, each guest floor was considered whole as a thermal zone. The 2-D Autocaddrawings of the hotel are depicted below. Furthermore, facilities as pool bar, restaurant,conference center were implemented in the analysis of energy consumption and variousenergy uses, but the design data regarding lighting power and heat gains from people andequipment for example were inserted according to their reference values from 1st TechnicalGuide of Greek Regulation for Greek buildings.

Image 2. Royal Hotel – SouthEast facade

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Drawing 1. Autocad drawings of typical floor. 1st and 2nd thermal zone

Drawing 2. Autocad drawings of typical floor. 3rd and 4th thermal zone

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Drawing 3. A typical floor Autocad drawing plan of Royal Olympic hotel

Drawing 4. Ground floor Autocad drawing – Pool bar, restaurant, conference room, outside space andlobby space

According to the Autocad drawings in the above images, the various thermal zones of the 3buildings are quoted in the following table, referring to one guest floor. Of course, floor

26

corridors are not excluded from the calculation of energy results since they are a fundamentalpart of the building. Corridors, guestrooms and rest facilities as lobby, restaurant, conferencecenter are analyzed separately in terms of input data used as air infiltration, lighting power,heat gains and coefficients associated with the occupant rate of people present andsimultaneity factors. The approach used in order to combine these data was to calculate theaverage values of these design data, which is quoted in section 3.3, proportionately with thethermal surfaces of each space used. It is noted that the whole thermal surface of guestrooms,including the 3 hotel buildings, is approximately 12000 m2, while the surface regardingfacilities, the majority of which is located at the ground floor, has been calculated to 3200 m2.

 Surface

(m2)ThermalZone 1

1085

ThermalZone 2

593

ThermalZone 3

373

Table 2. Thermal zone surface per floor – Guestrooms

3.3. Design data

In order Energy Plus to be able to identify energy loads and provide energy consumptiondata, some fundamental inputs are needed as air infiltration, heat internal gains from peopleand equipment, lighting intensity. Based on Greek Regulation for Energy Performance ofBuildings, these design data were inserted taking into consideration the reference levels forthese values, as shown in the below table. As explained in the previous section, the input datawere deduced, meaning that they were calculated according to which is the percentage ofcorridors, guestrooms and facilities in the whole thermal surface of the building. Accordingto this consideration, Table 3 presents this input data, that characterize and affect the finalenergy use of building for heating, cooling, DHW, lighting and equipment. In this point, it shall be underlined that some values like the lighting power or heat gainsfrom people or equipment or simultaneity factors are included in this thesis analysisaccording to hours of operation and simultaneity factors. In this scope, all electricalequipments are not in operation simultaneously when hotel guests are present in the hotel andthe use of equipment should be moderated according to this principle, which aimed to presentan equipment annual energy use that is realistic and does not lead to excessively highelectricity loads. Further information regarding these results are presented in the section 3.6. Before quoting the input data just referred, a table regarding the construction thermalproperties is given, which contains U-values of basic opaque and transparent buildingelements. It is underlined that, in the analysis conducted, the U-values inserted in EnergyPlus were taken according to the respective values from the Greek Regulation, and its revised2017 section [32].

 U-

values

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External walls 0.7External roof 0.5

External floor toground

1.9

Windows (Ug) 1.8

Column1W/m2

Daily hoursof operation

Coefficienceof presence of

people

Simultaneity factor

Ligting power 8.361 10.258 0.613 0.845

W/person

W/m2Coefficience of

presence ofpeople

Simultaneityfactor

Heat gains frompeople 63.39 6.35 0.61 0.42

W/m2Coefficience of

operationSimultaneity

factorDaily hoursof operation

Heat gains fromequipment 3.75 0.613 0.5 10.258

    m3/guestroom/year

Domestic HotWater 36.5

    Winter SummerDesign

Temperature (oC) 20 26

Relative humidity(%)

  35 45

              

 

Persons/ 100m2 of

surface

Fresh air(m3/h/m2)

Fresh externalair

(m3/h/person)

Air infiltration 15 3 20

Occupant rate 8

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m2/person

Table 3. Design input data [32]

3.4. Energy Mechanical Systems

For heating and Domestic Hot Water needs, two boilers are used separately for theseoperations. More especially, for the production of needed heating energy, the gas condensingboiler GB402 is used, constructed by Buderus. The nominal capacity of this boiler is 620 kWand its rate of efficiency is 96 %. It was considered that heating boiler GB402 operates inaverage for 8-10 hours in a typical winter day. This type of boilers are proper to operate inlow temperatures produced water of about 40-50 oC and are compatible with fan-coils used asheating terminal units which are designed to operate at this range of low temperatures. It isalso underlined that the seasonal efficiency of this type of boilers is not fixed and can reachup to 109.8 % in water temperatures 40/30 oC. For this case studied, the efficiency of theboiler was considered equal to 96 % as referred previously. Furthermore, the gas condensing boiler Logano S325 is one of the two DHW systems of ROhotel. This gas condensing low temperatures boiler operates at nominal capacity 70 kW witha rate of efficiency equal to 94 %. It was calculated that this boiler is responsible for theannual production of 6.4 kWh/m2 for DHW reasons and operates mostly during the winterperiod, since in summer and milder months solar panels contribute to DHW needs, asexplained in the below sections.

In addition, cooling energy which is the dominant use of energy in this hotel is covered bythe water-to-water heat pump Vitocal 300-G-Pro, with water temperature produced up to 55 o

C. This heat pump is used exclusively in summer months and operates at a nominal capacityof 177.4 kW with EER equal to 4.5. It is underlined that the technical characteristics of allthese systems referred are enclosed in the brochures enlisted in the references 33-34, in therespective section in the end of dissertation.

3.5. Relevant Climatic data of Athens

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In the current subsector, the main climatic data of city of Athens are presented, regardingtemperature, humidity and annual rainy days.

Figure 14. Average minimum and maximum monthly temperature of Athens[ https://weather-and-climate.com/average-monthly-min-max-Temperature,Athens,Greece ]

Figure 15. Average monthly sunshine hours of Athens [ https://weather-and-climate.com/average-monthly-hours-Sunshine,Athens,Greece ]

Figure 16. Average monthly rainy days of Athens [ https://weather-and-climate.com/average-monthly-Rainy-days,Athens,Greece ]

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Figure 17. Average monthly relative humidity of Athens [ https://weather-and-climate.com/average-monthly-Humidity-perc,Athens,Greece ]

3.6. The creation of 3-D model of Royal Olympic Hotel

The first step in the energy simulation of the hotel building is the 3-D construction inGoogle Sketch-Up, through the Open-Studio environment. Open Studio is a necessary tool soas to have a plug-in in Energy Plus software. In this case, Sketchup models have to be savedas .idf and .osm files in order to be imported in Energy Plus. Extensive effort was made inorder to draw the building in SketchUp, starting from the basement. All informationregarding insulation and construction materials, as well as internal and external walls,windows and all building elements that contribute to the building geometry and the creationof thermal zones, have to be involved in this step of analysis. The construction of the buildingin SketchUp using OpenStudio plug-in is the first and necessary tool in order to create amodel that will be identified by Energy Plus (.idf files) which will calculate the energyprofile of the building. Before presenting some images in which the building construction isshown, it is essential to present a small description of the fundamental operations and a basicworkflow of OpenStudio so as every lecturer to be able to understand the procedure of basicdesign through OpenStudio [30]. The workflow starts in the Extension options in upper toolbar of Sketchup in which adesigner can select OpenStudio plug-in to work on and create the needed drawings. Creationof the building envelope and defining attributes of each space used are the first steps adesigner should follow in order to create the OpenStudio model that he/she wants, as shownin the next image.

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Image 3. Basic Workflow Guide on OpenStudio

Working on left-hand side toolbar of OpenStudio is the main tool in the building designaccording to OpenStudio principles. In this toolbar, the insertion and exact definition ofbuilding space types, thermal zones, construction properties of building envelope and HVACsystems, together with their fundamental technical characteristics can be defined. In addition,the specific site information of the building can be inserted, allowing OpenStudio to operatein specific climatic characteristics. In Extension option of upper Toolbar, following OpenStudio User Scripts, there is BuildingComponent Library (BCL) option. From this option, as shown in the next images, there canbe inserted data inputs regarding space types, ASHRAE climatic zones and building types. InOpenStudio extension, there is also the option of creating standard building shapes and to seethe experimental workflow. All the above summarized information are summarized in thenext images and aim to guide the lecturers in the basic steps of OpenStudio design, as well asthey understand the initial steps in which the studied building was designed in GoogleSketchup and OpenStudio.

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Image 4. Basic Workflow Guide on OpenStudio [30]

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Also, using standing Sketchup tools permit to start the main construction building phase. Inthe lower toolbar, there are tools as Project Loose Geometry, new Shading Surface Groupand New Interior Partition Surface Group which are additional tools towards the design andconstruction of the building spaces and thermal zones and the insertion of shading overhangsor windows to wall ration. The Surface Matching Tool is useful to set the boundaryconditions. This is the necessary tool in order different thermal spaces to be connected. Aswell, Spaces Attributes tool gives the chance for assigning different attributes to each spaceand there is a matching render mode for each space attribute. All these characteristics anddesign features of OpenStudio are depicted in the below images 6 and 7.

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Image 6. OpenStudio basic design [30]

Image 7. OpenStudio basic design [30]

35

Based on the tools that were just explained, the evolution of the 3-D model in SketchUp isshown in the images quoted in this section. It is reminded that one of the basic purposes ofthis dissertation is the acknowledge of SketchUp software and the following images aim toshow the work that has been done in SketchUp through the design phase.

Drawings 5,6. Initial design of basementfloors in SketchUp (only for design practice purposes)

Drawings 7,8. Construction of a typical guest floorof Royal Olympic hotel

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This effort, depicted in the above screenshots, was made towards practice in OpenStudiosoftware design. In the screenshots following, the complete 3D model is described in thevarious design phases. The 3-D Model was created to assist with the simulation using theEnergy Plus Energy Simulation Tool. Energy Plus allows the user to enter all the neededgeometrical data manually. However, this method is extremely time consuming and there is afaster alternative. Google Sketch up is a drawing tool which, when combined with a plug infor Energy Plus, can create .idf files (energy plus input data files). These models not onlycontain the geometrical properties of the building, but they can also differentiate betweenthermal zones and contain information about the loads of each zone such as occupancy,lighting and ventilation loads.

After a zone’s size and position was estimated, it was then drawn in Google Sketch up alongwith other useful elements, like windows and doors, as shown below.

Drawing 9. Simple example of thermal zone design in Sketchup

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Drawings 10,11. Royal Olympic hotel – Design phase in SketchUp

38

Drawings 12,13,14. Design phase of Royal Olympic in Google Sketchup

39

Drawings 15,16. Design phase of Royal Olympic in Google Sketchup

40

3.7. Energy Plus Simulation – Energy results

The construction of the hotel building in OpenStudio, as described in the previous section,was the 1st part towards the experimental part of this thesis. In this stage, thermal zones of thebuildings were identified, as well as geometry and construction properties of opaque andtransparent building elements were inserted. Additionally, the energy systems and theirproperties were introduced in the model. All these elements were used in order to constructthe model and insert it into Energy Plus so as to calculate the primary energy needs of RoyalOlympic Hotel. The Energy Plus version that was used is EP Launch 8.1. Regarding the implementation of design data, Image 18 (below) shows the option ofentering internal loads in each zone. All the necessary data was gathered from Table 1according to the regulations and standards the official Greek Technical Guides, as reformedin 2017 edition [31]. Each surface of each zone was then made to interact with their adjacent surfaces. This wasdone by selecting a surface, pressing right-click and choosing the option Intersect Faces - >with Model as shown directly below. After this process was completed, from the tool bar ofGoogle Sketchup, the Matching Surfaces of selected objects across Zones was selected,which allowed the 3-D model complete interaction between all surfaces. A Visualrepresentation of these interactions can be viewed, as one of the results of simulation inEnergy Plus.

Image 8. Intersecting each surface with the adjacent surfaces in the model

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Image 9. “Matching Surfaces of selected objects across Zones” Tool

After the insertion of design data, internal loads and specific climatic data in this section,the basic results regarding the energy consumption and use of the building regarding heating,cooling, domestic hot water and electricity were calculated. The below tables depict all theinformation that include the energy consumption results of Royal Olympic hotel. After thefirst results presentation, some initial conclusions are quoted characterizing the initial thermalefficiency of the building and the initial energy profile.

Total Energy(GJ)

Energy PerTotal Building

Area( MJ/m2)

Energy Per ConditionedBuilding Area (MJ/m2)

Total SiteEnergy

5316.16 460.18 460.18

Net Site Energy 5316.16 460.18 460.18Total Source

Energy 10580.31 915.86 915.86

Net SourceEnergy

10580.31 915.86 915.86

Table 4. Site and Source Energy

  Area (m2)

Total Building Area 15552.31Net Conditioned Building

Area15552.31

Unconditioned Building 0

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Area

Table 5. Building Area

ElectricityNatural

GasAdditional

FuelDistrictCooling

DistrictHeating

Heating 0 0 0 0 1501.19Cooling 0 0 0 2084.43 0

Interior Lighting 781.12 0 0 0 0Exterior Lighting 0 0 0 0 0

Interior Equipment 188.21 0 0 0 0Exterior Equipment 0 0 0 0 0

Fans 0 0 0 0 0Pumps 0 0 0 0 0

Heat Rejection 0 0 0 0 0Humidification 0 0 0 0 0Heat Recovery 0 0 0 0 0Water systems 37.23 0 0 0 0Refrigeration 0 0 0 0 0Generators 0 0 0 0 0

Total End Uses 287.53 0 0 2084.43 1501.19

Table 6. End energy uses

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Table 7. End uses by subcategory

Table 8. Utilize Use per conditioned floor area

Table 9. Utilize Use per Total Floor area

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Table 10. Electric Load Satisfied

The above energy tables are some indicative tables, containing information about theenergy performance of the building. It should be mentioned that the energy results are basedon the initial design and the way the building was designed and simulated in GoogleSketchup and Energy Plus according to data as internal design parameter values forinfiltration, ventilation, lighting, people and equipment heat gains, energy systemsperformance. Therefore, the conclusions and the comments about the initial conclusions arestrongly associated with design data and their assumptions, maybe indicating changes thatshould be implemented in order to improve the energy profile of the building and make itrealistic according to the common trends that characterize the energy consumption of Greekhotels and towards the aim of assessing if it can be nearly zero energy Building. According tothis design way, the basic conclusions that were the leaders for the interventions made andthe refurbishment of the building are quoted below the following table, which involves thefinal energy consumption per year for each use.

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Heating Cooling DHW Lighting Equipment0

10

20

30

40

50

60

70

80

53.4

67.2

14.4

34.1

13.4

kWh/m2

Figure 18. Annual final energy consumption per use

1) The most dominant energy use is cooling energy, with 67.2 kWh/m2 annually. This can beexplained by the quite hot climate in Athens and the high solar radiation during summermonths. Royal Olympic hotel is located in the center of Athens, in a location hot and dry.Additionally, lighting and electricity consumed by equipment in facilities is twicecompared to the expected consumption, operating as heat gains in winter and reducingheating energy needs. Also, the big glass surfaces in the main facades of the building leadto higher cooling loads.

2) The total annual final energy consumption has been calculated to 183 kWh/m2. Asreferred in the beginning of the theoretical part, the average energy consumption amongEuropean hotels is 239 - 300 kWh/m2 and the respective value for the hotels in Greece is273 kWh/m2 annually. Therefore, the energy profile of Royal Olympic hotel is assessedas better, compared to these range values, indicating that the initial energy profile of thebuilding can be characterized as quite efficient, in terms of total annual consumption forall uses.

3) It is worthy to note that lighting energy has been calculated to 34 kWh/m2/year andenergy from equipment and electric devices 13.3 kWh/m2/year. These values areconsidered as higher than expected, despite the insertion of simultaneity factors andcoefficiencies of presence for people and equipment. It is believed that further energyaudit has to be made in the building in the form of a whole energy check, in order toinvestigate the high lighting loads of the building. Also, it is sure that these values comein a big percentage from the energy that is consumed in devices in facilities as restaurant,conference center etc.

4) For the above reasons, since quite efficient heat pumps and boilers are used for heatingand cooling needs, the interventions and the refurbishment proposed should aim to thereduction of cooling loads and a partial coverage of electricity loads. Furthermore, inorder to implement RES in the building, photovoltaic panels were considered to be input

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for the electricity production, since heating and cooling needs are covered by heat pumpswhich consume electricity in order to operate and the dominant energy use is forelectricity.

3.8. Energy Improvements Proposals

The first attemption to explain the energy profile of the building, as explained in the abovesections, leaded to excessively high lighting energy use and high people and equipment heatgains which increased strongly the annual cooling energy use and reduced the heating energyneeds. The latter one was a strong indicator that some inputs, as the daily hours of lightingoperation, were not inserted in the suitable and realistic way and, as well, some factors likesimultaneity factor were absent from the initial analysis. This was a strong mistake, leadingto a balance in which excessively high heat gains and lighting power leaded to the strongreduction of heating energy needs. This is, of course, opposite to the principles of appropriateenergy building design. Therefore, by inserting the appropriate corrections in all the relevantinput factors, as shown in Table 3, the energy balance of the building was transformed.Lighting energy use was approximately 25 kWh/m2, while annual cooling energy use wasaround 20 % greater than respective heating energy use. The latter is not so surprising,considering the local microclimate of Athens center and the long duration of externaltemperatures that exceed 25o C.

Looking further in the energy profile and energy use of the building, the building can beconsidered as quite efficient. Therefore, special attention is needed in order to implement theaccurate interventions in order to enhance as much as possible the energy efficiency by usingenergy sources that are environmentally friendly and lead to a quite enough energy usedecrease simultaneously with financial saves. Therefore, the two proposals chosen for RObuilding are the following.

1) Implementation of a photovoltaic system in building roof for the generation of renewableenergy on-site since the building facilities are based on electricity in order to cover theirenergy needs as discussed

2) The insertion of shading measures in order to reduce the cooling needs

Regarding the installation of PV system, the most dominant technical characteristics andfactors affected the PV operation are noted in the following guidelines and depicted in thebrochure that follows the main technical properties referred. It is referred that the PV studywas conducted in Energy Plus and the results, as well as the design of PV array and itsrelative parameters, were assessed through this energy tool.

a) The chosen model is Risen Energy SYP300M. The technical characteristics of this solarcell model are depicted and described in the following attached pictures. It is noted that

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solar cell efficiency is 15.45 % and nameplate capacity of solar module is approximately83 kW.

b) Roof covers an area of around 2000 m2. From this area, it was chosen to put PV panels inan available area of around 536 m2. This was chosen to be the total module area. Thesurface of each solar module is 1.95 m2 and it was estimated that 276 modules were used,from which each string consists of 12 modules and we have totally 23 strings that wereput in the PV area.

c) Regarding for the inverter, its capacity should match the capacity of the modules so thatAC to DC ration does not exceed the value of 1.15 and does not fall below than 0.9. Inthe present case, a value equal to 1.10 was considered as the optimal one.

d) The chosen inclination used was 35 degrees for the solar panels.

Image 10. Solar module – Technical characteristics

Regarding shading options that can be implemented in southeast and southwest facades,external shading devices were excluded as options for 2 main reasons. The first one isassociated with the architecture and the construction of the facades. Since the majority ofguestrooms in all the floors of 3 buildings have balconies, it is impossible to insert externalshading devices in these facades. Secondly, the implementation of shading devices isopposite to the readiness of owners and managers of RO hotel not to forward into actions thatcould change the external and architectural view of the hotel. Instead, internal blinds in therooms is an easier and more practical solution to be inserted to reduce somehow coolingloads, even though internal blinds are for sure less efficient solution since solar gains canpass through windows elements. Internal blinds are easier in their handling from hotel users,so as to let solar gains during winter to contribute in heating the rooms and partly protectinternal spaces during summer months from the high solar radiation.

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Image 11. Internal shutter blinds

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Image 12. Risen Energy SYP 300M – Fundamental technical properties

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Image 13. PV System array design

After the design of the PV system and the insertion of all the relative parameters in EnergyPlus, it was estimated that the annual energy production, in terms of renewable energy on-grid, is equal to 130,647 kWh or 8.73 kWh/m2, which corresponds to a percentage ofcoverage equal to 5.2 %/year, considering annual final energy. If the solar panels contributionto DHW needs is added, then the percentage of coverage from RES sources reaches 10.5 %in the new situation. Although, in order to evaluate the percentage energy savings, theimplementation of all possible measures should be firstly done. In the conclusions section,considering the effect of the implementation of PV system and shading devices, the finalassessment will be quoted as conducted. Regarding the total cost of the installation of the PVsystem, including investment, installation and maintenance cost, it was estimated to 104.500€. Further analysis regarding the financial feasibility of the investment in PV design and restenergy interventions is quoted in the conclusions section.

From the investigation conducted, it is easily understood that a PV system, located at theroof of the hotel, can contribute to the coverage of annual final energy needs by a percentagein a range of 5-10 % and is not able to cover a big percentage of internal loads. Therefore,since hotels are high energy consuming buildings, further investigation is proposed to bedone, including the overhauled equipment and the possible replacement with properly sizedenergy conserving alternatives.

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4. CONCLUSIONS

This thesis deals with the practice experience in use of Google Sketchup and Energy Plusthrough the energy simulation study of Royal Olympic hotel in Athens city center, after the1st part associated with the main benchmarks that characterize the energy profile of buildingamong the world, as well as some case studies that indicate the road to the implementation ofsmart energy management techniques and the optimization of energy balance of hotels.Among others, it was revealed that three main techniques that can be inserted and contributeto the optimization of the energy design of hotels is the continuous forecasting of electricityuse of occupants, the insertion of smart energy management techniques for the minimizationof simultaneity factors regarding the parallel operation of various electric machines and themaximum use of renewable energy systems for energy generation on-site and the maximumcoverage of energy use for heating, cooling, DHW, lighting and equipment.

Energy Plus uses parameters and factors as geometrical size and conditioned space,minimum and maximum set temperature, energy loads due to lighting, equipment and peopleheat gains, ventilation rates, building envelope thermal efficiency properties and energysystems properties. Moreover, the building was considered to operate for 8760 hours peryear. Initially, the energy results seemed to be distorted since the annual final energy use wascalculated to 250 kWh/m2 but lighting and equipment covered 75 % of this energy, whilecooling energy was calculated to be 8 times greater in annual terms compared to heatingenergy. Besides the fact that climate of Athens and the amount of sunshine hours per yearscan justify a slightly greater cooling energy than heating energy, this difference seemed tooexcessive to be real.

In fact, the distortion came from the assumptions associated with lighting and heat gainsfrom equipment and people. In the initial analysis, it was considered that lighting was inoperation for 18-20 hours per day and, in this case, all lighting equipment was operatedsimultaneously. Of course, this is not the real case scenario and simultaneity factors had to beinserted as design data for the operation of lighting, the presence of people in the hotel andthe use of equipment. Therefore, these factors were inserted, as well as assumptionsregarding the lighting power and heat gains from people and equipment expressed in W/m2.All the values associated with these data are referred to Table 3 in Section B3.3.

Because of the distortions referred in the last paragraph, lighting and equipment energyloads were too high that were led to too low heating consumption and, moreover, led to theextravagant difference between heating and cooling energy consumption. When the newdesign data were put in the model, the values of energy were differentiated. Total finalenergy in annual terms was calculated to 183 kWh/m2, from which cooling and heating wererespectively 62 and 52 kWh/m2 and lighting around 34 kWh/m2. The DHW needs werekeeped at a level of 14 kWh/m2. It is extracted that the insertion of realistic assumptionregarding the design data of the building in Energy Plus led to the real energy profile of thebuilding. It is repeated that the values for the design data were considered after takingseparately into account the respective design data for guestrooms and rest hotel facilities anddeduced to their surfaces, as indicated from Table 2 in this Experimental Part. Also, it is

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underlined that the final consumption is quite lower than the average energy consumption peryear for hotels in Greece, which is ranged to 200-300 kWh/m2, as referred to the 1st part. Thequestion that this thesis tried to answer is if this building can be transformed into Net Zero orNearly Zero Energy Building, according to the respective definitions [1]. As explained inSection B3.7, the two interventions proposed were the installation of a photovoltaic system inthe roof of RO hotel and the implementation of internal blinds in the southeast and southwestwindows of the hotel rooms. After the assessment of the final results, it was revealed that theshading effect of blinds was translated into the reduction of final energy use for 17.6kWh/m2, which is accounted for almost 16 % reduction in cooling energy. Hence, with theimplementation of a simple inside measure, the annual energy consumption flows to 165kWh/m2

Regarding the installation of PV system, it was revealed that the installation of the indicatedin Section 3.7 PV system can produce annually approximately 130,000 kWh which refers to5.4 % of new annual final energy use and a deduced energy of 8.5 kWh/m2.

The reduction from PV system seems to contribute for a low percentage in the coverage ofenergy use through RES, but the capability of PV panels with the solar cell chosen efficiencyand the surface covered can produce this result. Also, as referred above, the RES contributionto the building on-site energy in annual basis reaches 13 % approximately. Although, if weconsider it by its financial aspect, it will be worth the initial cost. If Net Present Value 10years approach is implemented with a discount rate of 10% and an electricity rate of 0.12€/kWh, then the financial parameters of the investment only in PV are quoted in the belowsector.

Column1 Cost (€)Original Investment 85.000

Installation Cost 8.500Maintenance Cost 8.500

Total Cost 102.000Discount Rate 0.10

Cash flow per annum 16.753Net present Value (12 years) 5.750

Table 11. Financial assessment of PV array investment

As it seems in the table that was quoted, the investment in PV is worthy to be done since itis repaid in approximately 12 years. The same conclusion is extracted if the payback periodcriteria is considered. In this case, the repayment of the investment is expected to be done inalmost 7-8 years, without considering the real value of money that is included in NPVcriteria. In NPV consideration, we should not forget the energy losses in the operation of PVsystem that exists in all PV panels after 15-20 years. Hence, it is expected that after 15-20years, the annual energy savings will be for sure lower than 16,753 €. For the time being, thepoint of interest is the annual energy savings and the feasibility of the investment in PV.

Therefore, if simple shading measures are implemented, then the annual final energy usewill drop from 183 to 165 kWh/m2 approximately. If a PV system with the properties referred

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will be inserted, then the balanced energy consumption drops down to 156.5 kWh/m2. If weconsider the only the PV installation in this small financial analysis, then the payback periodas extracted from the above table will be around 7-8 years and, according to NPV criteria, theinvestment is feasible after 10 years. If shading blinds are implemented in the interventions,then as referred to proposals section, the reduction in cooling energy is expected to be around17.6 kWh/m2/year which corresponds to a 16 % annual reduction. In this case, the paybackperiod would possibly be under 5 years of operation.

The most important conclusion of the thesis and the energy analysis conducted is that thisbuilding cannot be transformed and refurbished into nZEB, since PV system can produce 6-7% of total annual energy needs and can lead to annual cost savings around 10 % of theinitial cost. If the contribution of solar panels is considered to the total calculations, then thecoverage from renewable energy systems reach a little more than 10 %. Therefore, thisbuilding cannot become nZEB since it simply has not been designed as this from the initialphase of its construction. In order to make a building nZEB, heating and cooling systemshave to be renewable energy systems, like a geothermal heat pump, and combine energyefficiency properties as heat recovery. Furthermore, the first priority should be theconstruction of a building envelope that will be constructed in a way in which heating andcooling loads, meaning energy demand, will be minimized. Airtightness should be themaximum possible and, in many cases, mechanical ventilation with heat recovery should beimplemented. Especially in tertiary buildings like offices, hospitals and hotels, mechanicalventilation should be an important priority since energy losses through infiltration are oftengreater than considered and lead to higher energy demand. To achieve a zero or nearly zeroenergy balance, firstly energy demand has to be minimized and, then, the energy needs to becovered by the most energy efficient systems that reduce environmental impact.

Additionally, hotels is a building category with high loads in some uses like lighting andelectricity equipment or cooling in climates as South Mediterranean countries. In order tominimize these loads, an holistic energy audit should be conducted which involves, apartfrom the audit in internal climatic conditions, heat equilibrium of building envelope elements,audit of real energy systems technical characteristics and fundamental bills of electricity andfuels uses. These bills are a very essential element for the energy audit, since energyconsumption data are collected from the last 12 months before the beginning of the audit andthese data are statistically processed towards an energy profile that incorporates all therelevant past and present parameters.

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5. FIGURES – TABLES – IMAGES APPENDIX

FIGURES AND TABLES

  Page Figure 1 4Figure 2 5Figure 3 7Figure 4 7Figure 5 8Figure 6 12Figure 7 12Figure 8 15Figure 9 17Figure 10 17Figure 11 19Figure 12 20Figure 13 21Figure 14 30Figure 15 30Figure 16 31Figure 17 31Figure 18 45Table 1 14Table 2 27Table 3 28Table 4 42Table 5 42Table 6 43Table 7 43Table 8 44Table 9 44Table 10 44Table 11 52

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IMAGES AND DRAWINGS – APPENDIX –SUPPLEMENTARY MATERIAL

In this supplementary section, it is given an overview of images, drawings and schedulesthat were used towards the energy simulation, conducted by this thesis. The main sources,from where these data are come are Autocad drawings, drawings in Google Sketchup andimages of the building, as well as images describing the technical properties of the systemsused in the simulation.

  Page Image 1 13Image 2 24Image 3 32Image 4 33Image 5 34Image 6 35Image 7 35Image 8 41Image 9 42

Image 10 47Image 11 48Image 12 49Image 13 50Drawing 1 25Drawing 2 25Drawing 3 26Drawing 4 26Drawing 5 36Drawing 6 36Drawing 7 36Drawing 8 36Drawing 9 37

Drawing 10 38Drawing 11 38Drawing 12 39Drawing 13 39Drawing 14 39Drawing 15 40Drawing 16 40

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